1. Field of the Invention
The present invention relates to a light receiving member for electrophotography which exhibits an improved sensitivity to electromagnetic waves such as light (which herein means in a broad sense light such as ultraviolet rays, visible rays, infrared rays, X-rays and xcex3-rays.
2. Description of the Prior Art
The photoconductive material used to form a light receiving layer of a light receiving member for electrophotography must have an excellent sensitivity to light, high S/N ratio [photoelectric current (Ip)/dark current (Id)], an absorption spectrum compatible with the spectral characteristics of the irradiating electromagnetic waves, quick responsiveness to light and desirable dark resistivity. Further, the photoconductive material must not be harmful to the human body. This last characteristic is important for a light receiving member that is a component of an electrophotography device to be used in an office.
From the above-mentioned view point, non-single crystal silicon (hereinafter abbreviated as xe2x80x9ca-Sixe2x80x9d) has recently attracted attention as a photoconductive material. For example, Germany Patent Application Laid-Open No. 2746967 and Germany Patent Application Laid-Open No. 2855718 disclose applications in which a-Si is used as a light receiving material for electrophotography.
Further, Japanese Patent Application Laid-Open No. 57-11556 has disclosed a technology for improving the electrical, optical and photoconductive characteristics, such as the dark resistivity value, light sensitivity and the light response, the environmental characteristics at the time of use and stability against aging of a photoconductive member having a photoconductive layer made of an a-Si deposited film. According to this disclosure, a surface charge injection inhibiting layer made of non-photoconductive amorphous material containing silicon atoms and carbon atoms is formed on a photoconductive layer made of amorphous material as a matrix of silicon atoms.
Further, Japanese Patent Application Laid-Open No. 62-168161 has disclosed a technology using amorphous material composed of silicon atoms, carbon atoms and 41 to 70 atomic % hydrogen atoms to serve as a surface layer.
Further, Japanese Patent Application Laid-Open No. 54-121743 has disclosed an image forming member formed by an a-Si photoconductive layer and a supporting member, wherein a depletion layer is formed in the photoconductive layer so that the carrier generation efficiency is improved, the re-combination probability is lowered, and the light response speed and the residual potential are improved. Further, Japanese Patent Application Laid-Open No. 57-4053 has disclosed a very sensitive photosensitive member for electrophotography exhibiting excellent charge retaining performance in which a depletion layer is formed on a lower charge injection inhibiting layer which prevents the injection of carriers that have the same polarity as that of minority carriers.
FIG. 1 is a cross sectional view which schematically illustrates the structure of an example of a conventional light receiving member 200 for electrophotography. Referring to FIG. 1, reference numeral 201 represents a conductive supporting member, and 202 represents a light receiving layer made of a-Si, the light receiving layer 202 having a free surface 203.
A light receiving member for electrophotography of the foregoing type is usually manufactured in such a manner that the conductive supporting member 201 is heated 50xc2x0 C. to 400xc2x0 C. and then a film forming process, selected from a group consisting of a vacuum evaporation method, a sputtering method, an ion plating method, a heat CVD method, a light CVD method and a plasma CVD method, is performed making an a-Si photosensitive layer (the light receiving layer) 202. A method has been satisfactorily employed in which raw material gas is decomposed by DC or RF microwave glow discharge as to form an a-Si deposited film on the supporting member.
Conventional light receiving members for electrophotography have been practically used in a-Si copying machine that are not harmful to the human body and have high image quality and excellent durability. However, a necessity for many functions, excellent image quality and satisfactory durability has led to a trend of improving the performance of copying machines. The a-Si copying machine drums must be improved so that the overall cost is reduced. Further, the electrical characteristics and the durability under various environments must also be improved.
Electrical, optical and light conductive characteristics, such as the dark resistivity, light sensitivity and light response, environmental characteristics at the time of use, aging resistance and durability of conventional photosensitive material for electrophotography having the photoconductive layer formed with a-Si material must be further improved. For example, recent demands that electrophotography apparatus have higher processing speeds and form higher quality images have necessitated that the electrical characteristics and the light conductive characteristics of the photosensitive member for electrophotography be improved.
Specifically, in the case where a-Si is employed to form a photosensitive member for electrophotography there arise problems concerning optical memory, charging characteristics, residual potential, sensitivity and clear half tone which do not arise in the conventional low-speed charging-exposing-developing process. When using the conventional process, it has been shown that any improvement in the charging performance will deteriorate the residual potential and the optical memory. Therefore, the foregoing factors cannot be satisfied simultaneously while maintaining the respective desired levels. Moreover, employment of a-Si in a high speed process causes a problem of nonuniformity of half tone, that is, excessive roughness. In a case where a-Si material is used in a full color electrophotography apparatus, the optical memory and prevention of the half tone roughness can be further improved in order to improve the gradation expression and color reproducibility.
The conventional a-Si drum sometimes encounters a problem of an unsatisfactory copy density level if it is continuously used in an excessively high organic solvent concentration environment. Another problem sometimes arises in that a shadow-like defective image is formed. The foregoing problems must be improved to obtain stable images regardless of the environment.
Accordingly, the characteristics of the a-Si material, the structure of the layers, the chemical composition of each layer and forming methods have been improved at the time of designing the light receiving member for electrophotography.
An object of the present invention is to provide a light receiving member for electrophotography capable of overcoming problems experienced with the conventional light receiving member for electrophotography made of a-Si.
Another object of the present invention is to provide a light receiving member for electrophotography which has a light receiving layer comprising a non-single-crystal material which is composed of silicon atoms as a matrix, which exhibits electrical, optical and photoconductive characteristics that are always stable regardless of the environment for use, excellent light fatigue resistance, excellent durability such that it does not deteriorate even if it is repeatedly used, humidity resistance and in which the residual potential can substantially be eliminated. Another object of the present invention is to provide an excellent light receiving member for electrophotography capable of always forming stable images even under an adverse environment.
Another object of the present invention is to provide a light receiving member for electrophotography which exhibits excellent electrical characteristics in which no charging performance, residual potential, sensitivity and optical memory problems arise even if it is adapted to a high speed process electrophotographic apparatus, with which a clear images free from rough half tone image can be formed, which enables a high resolving power and high quality image to be obtained easily and to which a conventional electrophotographic method can effectively be adapted.
Another object of the present invention is to provide a SIMS interface evaluation system capable of accurately evaluating the interface steepness of a multi-layer film as compared with a conventional system.
According to one aspect of the present invention, there is provided a light receiving member for electrophotography comprising in sequence: a supporting member and a light receiving layer; said light receiving layer comprising in sequence at least a photoconductive layer and a surface layer thereon, said photoconductive layer comprising a non-single-crystal material containing silicon atoms as a matrix, and said surface layer comprising an amorphous material containing silicon atoms and carbon atoms as a matrix, wherein the carbon atoms are at least diamond-bonded and graphite-bonded, and wherein from 2% to 30% by number of the carbon atoms are graphite-bonded.
According to another aspect of the present invention, there is provided a light receiving member for electrophotography comprising: an electrically conductive supporting member; a photoconductive layer; and a charge injection inhibiting layer between said electrically conductive supporting member and said photoconductive layer and having a function of inhibiting injection of carriers from said supporting member side into said photoconductive layer, wherein said photoconductive layer and said charge injection inhibiting layer are each a non-single-crystal material mainly composed of silicon and containing hydrogen, said photoconductive layer has a reduced polarity p-type conduction when said light receiving member for electrophotography is positively charged and has a reduced polarity n-type conduction when said light receiving member for electrophotography is negatively charged, said charge injection inhibiting layer has a reduced polarity p-type conduction when said light receiving member for electrophotography is positively charged and has a reduced polarity n-type conduction when said light receiving member for electrophotography is negatively charged, and said charge injection inhibiting layer has a density of states from 1xc3x971017 cmxe2x88x923 to 5xc3x971019 cmxe2x88x923.
According to another aspect of the present invention, there is provided an interface evaluation system of a type measuring the interface steepness of stacked films by a secondary ion mass spectrometry, said interface evaluation system comprising: a unit for calculating the scatter, which is the reference of the interface steepness, from a result of a secondary ion mass spectrometry of a subject element in the direction of the thickness; and a calculating unit for displaying said scatter with respect to the subject parameter of the secondary ion mass spectrometry.
Other and further objects, features and advantages of the invention will be appear more fully from the following description.